Laser light received by a detector and modulated has heretofore been transmitted through glass fiber cables operated in a unimodal way. Such core fibers are especially well suited for the transmittal of communication due to the minimal transition time distortion. The glass fiber cables have been surrounded by coating glass and the core fiberglass diameter has been of the magnitude of the light wave length, and the coating diameter has been approximately forty times as large, giving a diameter of the entire system of approximately 80 to 100.mu.m. Such a transmission system has been very satisfactory, but it has been difficult to connect two glass fibers in end-to-end relation or to connect the glass fibers between a laser as a transmitter and a detector as a receiver.
The present invention, therefore, is to create a simple and efficient connection between two core glass fibers, connecting the core fibers in end-to-end relation and attaining a low disturbance of the light expansion at the connecting point.
In order to solve this problem, I provide a light conductive glass fiber consisting of a core fiber and a coating glass arranged around the same and a second similar core fiber in which the ends of the first and second core fibers to be connected are thickened at their connection point, to attain an index of refraction profile which steadily declines from the middle to the peripheries of the fibers.
Preferably the core fibers are drawn to have thin ends increasing in diameters toward their connected ends to attain thickened core fiber ends of a diameter of from 0.5 to 5mm. This will reduce the index of refraction at the thickened ends of the core fibers in accordance with a parabolic function, from the middle towards the peripheries of the fibers.
In order to facilitate the connection between the two fiber ends, the thickened portions of the core fibers are imbedded in the mass, as for example, a synthetic resin, which may be machined to provide a fitting area for receiving a centering ring, holding the core fibers in end-to-end relation with respect thereto.
An object and advantage of the present invention, therefore, is to provide a simple and improved construction and arrangement of core fibers and connecting means therefor connecting the fibers to have a low disturbance of light expansion at the connecting point.
Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure.